The License

AGG 2.5 License

Anti-Grain Geometry is an Open Source, free library released under the terms and
conditions of GNU GPL license.

Anti-Grain Geometry (AGG) - Version 2.5
A high quality rendering engine for C++
Copyright (C) 2002-2006 Maxim Shemanarev
Contact: mcseem@antigrain.com
mcseemagg@yahoo.com
http://antigrain.com
AGG is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
AGG is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with AGG; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA.

The previous versions have more liberal licences that allow
for free use in commercial software.

Commercial licensing is also available upon request.

AGG 2.4 Licenses

Anti-Grain Geometry Public License

Anti-Grain Geometry - Version 2.4
Copyright (C) 2002-2004 Maxim Shemanarev (McSeem)
Permission to copy, use, modify, sell and distribute this software
is granted provided this copyright notice appears in all copies.
This software is provided "as is" without express or implied
warranty, and with no claim as to its suitability for any purpose.

Modified BSD License

Anti-Grain Geometry - Version 2.4
Copyright (C) 2002-2005 Maxim Shemanarev (McSeem)
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
3. The name of the author may not be used to endorse or promote
products derived from this software without specific prior
written permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

Please mention the authors in any work derived from Anti-Grain Geometry.

General Polygon Clipper (GPC) License

Anti-Grain Geometry distribution package includes General Polygon Clipper (GPC) by Alan Murta. GPC has
a different kind of license that allows you to use Alan's work for free
only in non-commercial software. Below is the full text of it.

http://www.cs.man.ac.uk/aig/staff/alan/software/
Author: Alan Murta (email: gpc@cs.man.ac.uk)
Version: 2.31
Date: 4th June 1999
Copyright: (C) 1997-1999, Advanced Interfaces Group,
University of Manchester.
This software is free for non-commercial use. It may be copied,
modified, and redistributed provided that this copyright notice
is preserved on all copies. The intellectual property rights of
the algorithms used reside with the University of Manchester
Advanced Interfaces Group.
You may not use this software, in whole or in part, in support
of any commercial product without the express consent of the
author.
There is no warranty or other guarantee of fitness of this
software for any purpose. It is provided solely "as is".

However GPC is not an obligatory part of AGG and can be easily removed.
You just don't copy (or remove) agg2/gpc/* and you can also
remove agg2/include/agg_conv_gpc.h in case if the GPC license does not
allow you to use it.

GPC is a General Polygon Clipper that performs boolean operations
on polygons (poly-polygons to be exact). In AGG you can get the same
visual result using Scanline Boolean Algebra. It operates with scanline
shapes and in average works 5-10 times faster than GPC. See:Demo scanline_boolean.cppDemo scanline_boolean2.cpp

You need GPC if you really really want to have vector data in the
ouput. For screen graphics of any kind Scanline Boolen Algebra is quite
a good replacement.